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Sustainable Community Design

Parker Snyder

Independent Research Thesis

Submitted Respectfully

May 2, 2003

Purdue University

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TABLE OF CONTENTS

Changes in Environmental Thought Concerning Development ............ 1 How Communities Structure our Dominant Paradigm .......................... 4 Case Study: Village Homes Sustainable Design ................................ 6 Land Use/ Site Design Fig 1. Village Homes Site Plan Table 1. Land Use in Development Energy Efficient Design Table 2. Residential Energy Use Resource Utilization: Water, Waste, Agriculture, People Fig 2. Summary of Village Homes: PROFILE The Criteria for Sustainable Development ............................................ 13 Fig 3. Conceptual Diagram The Criteria for Sustainable Design Designing for Sustainability in Residential Development ................ 15 Energy Supply/ Efficiency ................................................................... 16 Designing to Maximize Energy Efficiency Super Insulated Homes Fig 4. Super Insulation Wall Details Passive Solar Gain Homes Fig 5. Southern Orientation to Site Layout Fig 6. Passive Solar Water Heating/ Breadbox Active Solar Heating Systems Fig. 7. Photovoltaic Array Fig 8. Systems Solar Design in Residence Waste Treatment/ Management ......................................................... 24 Construction Waste and Embodied Energy Consumer Waste Byproducts Sewage and Greywater Fig 10. Wetland Schematic Drawing Fig 11. Schematic of Constructed Wetlands Summary of Sustainable Residential Development ............................... 28 Appendix ................................................................................................ 29

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Formerly environmentalism was the realm of the fringe—a group of eclectic

“greens” who held a deeply ecological view of the world. The group arose in the 1960s and 70s in response to environmental degradation and the subsequent cover-ups by governments and corporations. These environmentalists considered industrialization and development as unfavorable because it meant destroying the natural world. Progress connoted degradation and depletion.

Scientists, politicians and professionals were alienated from these activists whose

propositions seemed to undermine their positions of power. To get an idea of the nature of this tension, recall the in violent confrontations between activists and officials in trade summit meetings in Seattle, WA. It seems, at first consideration, that the relationship will always be one of conflict. But in the last 15 years, the dominant paradigm concerning environmental thought has undergone a radical transformation. Men and women in all manner of industries and professions are realizing the inherent benefits of integrated, holistic design.

An ecologically conscious structure considers human and material systems. A

holistic approach produces an aesthetically pleasing work environment. Employee productivity increases and owners receive unseen returns on investment. Recently design professionals—architects and engineers among them—have been acknowledging the benefits of green design and have begun retelling a similar story: for the first time in modern history our children may live at a standard of living lower than our own. The world’s resources are finite and depleting. Arable land, fresh water and air quality are being degraded. The plants that produce the world’s oxygen are being harvested at appalling rates. The Earth’s interrelated systems are threatened.

Most no longer debate these statements—only the extent and the degree to which

they are true. But there are difficulties arguing what might appear overwhelmingly true at first glance. For example, consider the often quoted argument that oil reserves are finite and will be depleted within say 50 years. It is misleading to say that reserves are finite in the short term because exploration will turn up more and more if an economic incentive in present. But one point of almost universal agreement is that the Earth’s resources are distributed inequitably. Powerful organizations and armies will have to ensure access to these resources—a dangerous and expensive proposition.

What are design professionals saying to those who are willing to listen? Owners

of wealth and capital are can do more with less and make more money in the process. In fact, to remain competitive in global markets they will have to improve their efficiency. The result has been a synthesis of the business and environmental values.

The arena of sustainability is doing more with less, preserving what remains of

the natural world, and making money in the process. The word is a potent one involving a synthesis of economics, politics and design science. And excitingly, the drive to do more with less is being led by design professionals who are working to apply ingenuity and hard science.

Changes in Environmental Thought Concerning Development

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New terms have entered the engineer’s vocabulary—ecological efficiency, natural capitalism and sustainable development. The new language has accompanied new developments in thinking. No longer can we look at a road and an automobile as we did previously. A vehicle is the terminus of a long sequence of events preceding its arrival on the road. The metallic ore must be extracted in diverse geographic regions. The ore has to be transported long distances to be refined. Silicon must be mined and refined for electronic components. Many production processes are necessary in the production of the automobile that have little to do with driving. When the relationships are described on paper the result is an intricate web of interrelated component processes—all with the capability to be redesigned, made more efficient or done away with altogether.

Buckminster Fuller, an early leader in resource efficiency and utilization, believed

that the modern house has evolved little since the industrial revolution. We still build structures of brick and stone and mortar that are similar to those we built a hundred years ago. Fuller believed that the residential construction industry had progressed comparatively less than other industries because of our failure to see how unconventional technologies and ideas could be applied. It is my hope to address the residential construction industry in this report and how we can better design for sustainability.

Most developers have accepted conventional design models. The emergent pattern

involves track houses centered on plots at their maximum density, wide streets and sparse landscaping. Utilities run underground and out of sight. Modern sewage systems distance us from the treatment of waste. The procurement and production of raw materials for building supplies goes unseen.

The actual cost of a development is not considered by the developer because he

will not be paying for poor design. (No one but the unhappy homeowner who pays the bills knows anything about the resources being wasted.) Potential for sustainable design goes unrealized because conventional design is predicated upon maximizing profit with little to no intellectual investment. But both the developer and homeowner have much to gain from smart design—profit margin may be higher and utility costs lower.

The automobile is the motivating principle for the design of our neighborhoods.

In North America, it fashions our understanding of the way we relate to human beings. (Most people will only greet the person who lives next to them through the windshield of their car). Transportation is a function of our value for mobility and freedom. But our desire for mobility and freedom is a function of the availability of petroleum. In turn, enormous and powerful business mechanisms must drive production. Political systems must ensure our access to those resources. We must ask ourselves, is our desire for mobility and freedom important enough to sacrifice economic and social security?

Many find it unreasonable to consider alternative forms of transportation. The

modern development is situated far from our places of work and study. Residents drive many miles acquiring resources and enjoying leisure time. To design sustainably, one must consider the whole system and all its component processes and loops, while acknowledging the motivating principles behind human behavior. In other words, it’s not enough to design a bike path; you must give the resident a reason to use it.

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To incorporate sustainable design, we must adopt a systems view. Once we have defined the system we must recognize that it is always enhanced by acting in the interest of other people. If we design for one another—for community—than we will ensure that the world our children inherit from us is one capable of meeting their needs.

I will examine the methods, mechanisms and the ideology of residential development. I will make the argument that conservation and preservation of the Earth’s resources for future generations involves changes in traditional methods of building and design. I will argue that residential development must be made more sustainable by incorporating a host of design principles that enhance the well-being of the people who live there. I will demonstrate that sustainable design has merit in resource savings, cost savings and financial returns to the developer.

Of fundamental concern is the quality of life for all people. Those interested in

improving true quality of life—looking at how good it can be—will want to read on. The few who find this endeavor fascinating—the engineering science of the 21st century—might be the ones who enable our children to enjoy a standard of living above the one we enjoy presently. If we continue to employ conventional models it is unlikely that they will.

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Houses and neighborhoods fashion people’s understanding of the world. Recall

your own home and the neighborhood you grew up in. Were your expectations and values formed by the character of the neighborhood? If neighbors are friendly it is likely that one matures with an understanding that most people are indeed friendly. Likewise, if the neighbors are unfriendly it is likely a person will be disenfranchised from people as they grow into adulthood—or at least more suspicious of people.

If the experiences of your youth were disjointed, accompanied by frequent

relocations, or if the community you grew up in was inhospitable or unfriendly, perhaps your dominant ideas about the world were those of hostility and inhospitality. Similarly, if you were welcomed in your community and the experiences of your youth were healthy and uplifting, might not your dominant paradigm be one of security and predictability?

Consider “waste disposal” as one example of how patterns of behaviors influence

our modes of thinking. It is likely that a man or woman arrived regularly at your door to dispose of your household waste. The waste left your sight and perhaps you gave little attention to its disposal. Waste begins to be defined at a very young age. Everything that is “thrown away” is waste—regardless of its capacity to be reused or resold. As a person who grows up in a conventional neighborhood, it is difficult to conceive of the waste stream as anything other than a “one way street.”

We are all shaped by our experiences growing up. If there is to be change to our

neighborhoods—and our expectations of consumer production and consumption behavior—than we need to reevaluate the character of our neighborhoods objectively. How are we going to accomplish social, environmental and economic objectives without restructuring and rethinking the incubator for the growth and maturation of our ideas?

This paper makes the argument the Earth’s resources are finite it is imperative

that we begin to design for sustainable objectives. And because our primary residence is the mechanism through which we first shape our ideas about the world, our efforts should begin in the design of our homes and neighborhoods. I will argue that we should design and construct residential developments to maximize tangible and intangible benefits to both the individual and the community. It is my hope to enumerate changes necessary to the character and structure of our neighborhoods. It is likewise my hope to show how these changes translate into benefits to the homeowner and the community.

Reforming the dominant residential sub-development paradigm will involve incorporating design principles that promote community, social health and ecological responsibility. The design principles ask us to reevaluate traditionally accepted structures and methods substituting them with others that have proven effective in achieving positive ends.

Modern development consists of main arteries connecting secondary streets. The homes face squarely to the street. Each house has a sizeable setback and the streets are wide—often three or four car widths. The driveway intersects the street perpendicularly and the garage is the foremost architectural feature. Houses are designed around the

How Communities Structure our Dominant Paradigm

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garage often the dominant architectural feature. The streets intersect at four way intersections. The inhabitants come and go at regular intervals in their automobiles because services are far from their place of residence.

The houses are served by a network of utilities that are structured around a central

system. Electricity is generated far from the people it will serve and is fed to the development over miles of high voltage transmission lines. Water is delivered via a central delivery system after being drawn from a local source. The treatment and transportation of potable water is a process that is far removed from the people it will serve. Waste streams into a neighborhood are linear. Products arrive in the houses transported many miles from the location they were manufactured. After the products are used, the waste material is deposited locally at a waste facility.

Human waste is transported through a network of pipes and pumps to be treated at

a remote site. Information flows into the community via cable, telephone and satellite communication devices. Electric signals are transmitted through a host of different mechanisms to arrive in the household of the end user. Goods are stored locally until they are used by an internal network of devices and machines. The modern age has afforded mankind opportunity to preserve food until it is ready to be consumed and to perform mundane tasks with little to no investment of time and energy.

All these processes, quite subconsciously, affect our modern paradigm concerning

the world we live in. It is difficult to imagine a world where resources are finite and scarce for some when all manner of goods and services are provided inexpensively and reliably.

Likewise, it is difficult to conceive of neighborhoods fraught by poverty, crime

and unrest when the primary community you live in suffers from no such malady. I believe services should be provided timely and reliably, such that the residents’ time may be more appropriately spent making a living and raising a family. However, the world we live in has a finite resource base and a limited capacity to absorb or mitigate the effects human populations impart on natural ecosystems.

Man is inextricably dependent upon natural systems to meet his needs. For

example, the atmosphere has a finite capacity to absorb carbon dioxide. Mankind cannot convert carbon dioxide to oxygen in sufficient quantity on his own. He depends upon plants to accomplish this task.

Regardless of the moral imperative we have as human beings to address the issue

of finite resources and the imbalanced global consumption of these resources, our lives in community developments can be improved–quantitatively and substantially—by reevaluating the primary character of residential development.

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Village Homes in Davis, California is a modern success story for ecological and

community friendly design. The project was conceived of in the 1970s, partly in response to rising energy costs and alienation from conventional development. Michael and Judy Corbett worked with local developers to design a residential development that was centered on people rather than the automobile. Rocky Mountain Institute, which promotes “green” design in modern planning and development, praised the successes of Village Homes remarking,

Over time, Village Homes has become a dearly loved neighborhood, with lower utility and food costs and a strong community fabric, because it was designed to endure. The turnover rate in Village Homes is very low, with residents often opting to remodel and add on rather than move to a larger home. When homes do go on the market, they sell at a premium price and faster than homes in nearby subdivisions.1 The Corbetts realized that a development would be successful if it was centered

on the residents. Therefore, the homeowners were involved in the planning of the development and are now actively involved in its management. In every way, the people were responsible for the community they built. But what design principles made Village Homes successful as an ecologically responsible development? What design principles centered community life on the people rather than on the street and automobile? I will examine the design principles utilized by the Corbetts understand the nature of sustainable community design. It is my hope to survey the principles in Village Homes and then provide detailed design information later in the report. Land Use/ Site Design/ Orientation Designers wished to develop the 70 acre site to maximize their use of resources. Streets were narrowed from a typical 32-40 ft to 25 ft. House setbacks facing the roadways were shallow but backyards were larger compared to conventional development because some areas were shared in common. Houses were connected with bike paths that bisected the “green belts” created between rows of homes. Parking bays were created to substitute for large garages and on street parking that was intentionally eliminated because of narrower streets. Through traffic was greatly reduced because of cul-de-sacs. Intersections were overwhelmingly “T” shaped for several reasons. “T” intersections reduce speeding and direct drivers’ attention to the surroundings. The designers realized Village Homes would be situated on viable agricultural land. Personal agricultural spaces were included and a 15 acre community owned plot was developed. Overall, the land was designed with an understanding that land is a resource.

1 Village Homes, Davis, California, Rocky Mountain Institute, page can be found at http://www.rmi.org/sitepages/pid209.php

Case Study: Village Homes Sustainable Design

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Shade trees were positioned along the road surfaces to absorb incident radiation. Landscape cover was provided to eliminate the “island of heat” that results from vast, open paved surfaces. Houses were oriented east-west to allow south facing walls to absorb peak sun during the winter months. The designers used discretion laying out the site to minimize energy loss and to maximize energy gain during winter months. A summary of the typical allotment for land use compared to conventional development is provided in Figure 2.

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Cul-de-sacs reduce flow through traffic

Curved Streets

East-west Orientation

Bike paths, community space

Community facilities provide employment

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Land Use Allocation of Village Homes vs. Typical Development

Table 1 Land Use in Development Comparison

The plots decreased in size by 40% but common areas increased by 15%. Houses

were smaller than those found in conventional development. Driveways decreased in size. The south facing walls, because they were predominantly windows, were surrounded by small courtyards. The courtyards provided the privacy that is typically provided by a large patio or deck in the rear. But Village Homes used the “backyard” as the geographic locus of activity. Therefore, the small, front yard functioned as the private space for the homeowner. The center of activity was relocated from the street to the backyard where homes were connected by bike paths and green spaces. Concerning land use, it is important to recognize that each development will have different resources. Agricultural land and sunshine were plentiful in Davis, California however lacking they might be in the northeast for example. Therefore, it is important for the property manager to recognize the assets of any new development. Energy Efficient Design Energy conservation is largely a function of design and the largest savings in energy are acquired before the homeowner ever moves in. Designer’s oriented all the houses east-west to allow a large south facing wall to absorb the sun’s energy during the winter months and reducing homeowner dependency on auxiliary heat. The technique, known as “sun tempering” can reduce dependency on energy for heating and cooling by 20-50%.2 Facing the houses east-west, even though the streets were gently curved, was a difficult proposition for the local municipality which insisted on a perpendicular orientation. Solar access issues arose, because of the importance of the sun for heating and cooling. Therefore, architects studied solar rights with small scale models to ensure that incident radiation was not blocked. Solar energy was used for water heating. For

2 Bainbridge, David, Corbett, Judy, Hofacre, John, Village Homes Solar House Designs, Rodale Press, Emmaus, PA, 1979, p 20.

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seven months of the year, residents are on full solar water heating and 60-80% of the time during the rest of the year.

Smaller streets and overhanging vegetation reduce excess heat common to paved surfaces. Designers expect a 10ºF reduction in the average air temperature during hot summer days when trees are fully grown. Open back yards allow cool breezes to flow through the development in the evening.

The breakdown of energy use by a resident in Village Homes is summarized in

Table 2 and based on a survey conducted of energy costs.3 The distribution would be different for conventional development. More energy would be used for heating and cooling interior spaces. The pie chart shows that transportation is the largest component of energy use. Therefore, to make the development more sustainable designers encouraged pedestrian and bicycle traffic.

Energy Use by Residents of Village Homes

Auto-transportation,

50%

Heating, 18%

Cooling, 7%

Hot water, 5%

Refrigerator & Freezer, 8% Lights, tv,

clothes dryer, 12%

Table 2 Residential Energy Use

Most people use the automobile as their primary form of transportation. The

residents of Village Homes were no different. To encourage bicycling and pedestrian travel the designers implemented an extensive network of bike paths. Corbett described the motivation for a connected network of bike paths:

It was deliberately made easier and faster to walk from one area to another in the development than to drive there. The whole network is tied into the city bikeway network. Numerous recreational facilities and the provision of jobs for members of the community in a commercial center and in agricultural projects will reduce the dependence of residents on the automobile.

Davis, California benefits from an already well integrated bicycle transportation system allowing the designers to integrate the local network with the broader city based 3 Bainbridge et al., p 19.

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one. However, if designers are to seriously consider a more sustainable residential development the importance of alternative forms of transportation cannot be understated. A timely bus system, with access to and from the development, is likewise an important consideration in design. Resource Utilization: Water, Waste, Agriculture, People

Measures to reduce water consumption were taken. Natural drainage methods

were utilized to reduce the costs of expensive and unnecessary underground piping. The money saved was used for additional landscaping. Native species were planted—those that had become accustomed to local rainfall patterns—and were less dependent upon irrigation. Unfortunately, grew water and septic systems failed to receive approval from local authorities—designers had considered cluster septic systems and compost toilets but could not convince the city of their merits.

More durable materials were selected for construction to reduce the waste from

resurfacing, rebuilding or refinishing. Concrete for bicycle paths and parking bays was more expensive but has greater lifecycle duration than asphalt. The roofing tiles used on most houses have a lifecycle of around 100 years.

As mentioned, the land was useful for agricultural production. Personal and

community agricultural plots were developed. Corbett notes that the community values these plots because they are centered on community. In order to plant, grow and harvest, the residents must collectively manage the agricultural land. A group of residents manage the produce, sell it at a profit and reinvest the profits into the community.

People are considered the most important resource of the Village Homes

community. Local employment opportunities were created for residents partly to minimize dependency on automobile travel. Commercial space is present in the development. Apartment complexes are intertwined with residences. The 70-acre development was designed for people of diverse income ranges. In summary, Village Homes was the result of ingenuity, a commitment to sustainable principles and the participation of the homeowners in the design. Similar developments are present throughout the United States and deserve the attention of any developer that wishes to maximize the return on investment. Figure 2 provides a summary of the Village Homes development:

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Figure 2 Summary of Village Homes Davis, California

PROFILE: Project Name: Village Homes Location: Davis, California Developer: Village Homes Contact(s): Michael and Judy Corbett, Local Government Commission Date Completed: 1981 Project Size:

Site (gross land area): 70 acres Building (gross building area): 32 acres Project Description: Residential. Planned community of single family detached homes and apartments (240 units); 12 acres of greenbelts and open space; 12 acres of common agricultural land; and 4,000 SF of commercial office space.

Hard Costs: Site Acquisition Costs: $434,000 (1975) Site Development Costs: $2.3 million

Soft Costs: Marketing/Leasing: Marketed initially by developer, now largely by word of mouth Amenities: $313,107 for swimming pool, bike paths, landscaping Initial sale price per unit: $31,000-$75,000 Types of Financing: Limited partnership for first 10 acres. Infrastructure lender Sacramento Savings and Loan. Initial option on the land $10,000; 13 investors raised $120,000; first bank loan $170,000 for first 10 acres (1973). Bought land in increments over a five-year period, developed in five phases. Average Development Cost/SF: $38 (1980) Total Return on Investment: Original investors made a profit of 30% per year Notable GD Features: Platted to ensure solar access. Active and passive solar home designs. Natural drainage systems based on Ian McHarg's model. Pedestrian friendly design with bike paths and narrow streets. Edible landscaping and organic agriculture. Results: Known as the "granddaddy" of green developments. In 1995, homes sold for $10-$25 per SF over standard homes in the area. Homes have a low turnover and sell faster. Very low crime rate in neighborhood. Lowered ambient air temperature by 15°F by reducing paving. Surface drainage system saved $800 per lot, which was applied toward additional landscaping. By 1989, much of Village Homes' residential food was produced in the neighborhood. Annual household bills range from 1/2 to 1/3 less than surrounding neighborhoods. 80% of the residents participate in various activities promoted by the development. Average number of cars per household is reduced from surrounding Davis neighborhoods.

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A sustainable development is capable of meeting all its needs internally. The development must provide commodities and services at zero waste for its occupants while being “isolated” from centralized infrastructure. It must be able to produce its own food supply, supply its own electricity and process its own waste. There is no net flow in our out of the system save for energy, water and information. As the development tends toward sustainability the material flux goes to zero. Ideally formulated, the only flow across the system boundary is energy and information.

Figure 3 Conceptual Diagram of Sustainable Design

The definition for sustainable development which I have put forth is obviously

ideal—no development by such a definition can be considered sustainable. Consider further that a development may impinge upon neighboring developments from being able to supply their own needs even if it qualifies as sustainable. For instance, if one development utilizes local agricultural land for producing its own food supply it follows that less land will be made available for neighboring developments. If a development draws from an underground aquifer, it may draw water from neighboring sources. But consider sustainability and functional autonomy as synonymous. In this way, we define a standard for sustainable design that motivates the character of our design.

The criteria for sustainable design:

• Energy needs are met locally by renewable resources • Waste is processed locally or recycled • Food energy is produced locally • The development is constructed from durable materials • Non-material needs such as “community belonging” are met

Model of Sustainable Residential Design

The Criteria for Sustainable Development

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Energy needs are met locally by renewable resources A sustainable supply of electricity is derived completely from solar energy because it is the only energy source that can be entirely localized. (Neglect the negligible energy input that goes into producing the solar cells). Solar energy does not deplete the net energy supply in the Earth’s biological and inorganic energy reserves.

Waste streams are processed locally via systems approaches – Human waste is neutralized through bio-organic processes and returned to the soil. Recycling closes the consumer waste loop. Waste becomes the input for new consumer products. All materials are designed with the intent that the waste will be recycled. The conventional term “waste” ceases to have meaning because waste becomes the input in the manufacturing process.

Food energy is produced locally – Food travels thousands of miles before it is consumed because of economies of scale and the margins of trade. Sustainable development must meet a portion of the nutrient intake of its residents to decrease the energy demand associated with long-distance transportation. Residents’ diets should be supplemented by locally produced food. This is a criterion of sustainable design because it takes non-renewable energy to manufacture and transport food products from producer to end user in a conventional food supply model. In addition, locally produced food promotes other criteria such as “community belonging.” Designers must consider food production if they wish to address sustainability.

The development is constructed from durable, low-embodied-energy materials – The embodied energy of a material is the amount of energy that goes into manufacturing and placing a material. Wood, brick, stone, concrete, clay and mud vary in the embodied energy associated with the product once it has been utilized in construction. It should be a sustainable designer’s initiative to minimize the embodied energy of the material while maximizing durability.

Non-material needs such as “community belonging” are met – The non-material needs of the residents are addressed in sustainable design because people are the value for which the development exists. Design enhances the quality of the relationships between people. Designers provide the structure and facilities for gatherings—and promote reasons to get together by smart planning. Community facilities are constructed that promote local employment.

It is my contention that design in the future will tend toward autonomy and away

from centralized infrastructure. More services will be provided locally and a range of income levels will be accommodated. Mixed use implies a variety of purposes. No longer should residential development be isolated from places of work and leisure. I contend that a decentralized system is much safer—as the gap widens between rich and poor it will be increasingly necessary to design for issues of security. The public can be sold on the basis of personal security. Just as mobility and convenience were watchwords of the 20th century, security and reliability will be the watchwords of the 21st century particularly as demand for land, water and energy increases in a world with finite resources.

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Please note that sustainable design isn’t good and unsustainable design bad. The discussion is not black or white—nor should it be. Instead, sustainable design recognizes that value can be added if holistic approaches are taken. The sustainable model is a closed system—that is to say that residents’ need are taken care of at a local level. But the system is never completely closed because people have to leave their homes—what a boring life if they didn’t! Instead, we design for functional autonomy to utilize the benefits of systems design. Waste becomes the input for other component processes. Furthermore, we must recognize the tradeoff of a centralized system. Centralized energy supply sacrifices efficiency for reliability. If we design for sustainability we maximize both reliability and efficiency.

Designing for Sustainability in Residential Development This section of the report presents specific recommendations for developers who want to design for the criteria of sustainability. Because I want to be focused and thorough, rather than broad and general, I will limit my discussion to just two criteria of design. I will consider energy supply/ efficiency and waste treatment/ management. Both issues are fundamental because they are related to other criteria. Designing for one means designing for others. Keep in mind that solutions are specific to different regions of the country. A well designed residence/ community in Boise, Idaho will necessarily have different features than one in Tuscon, Arizona. The principles will be the same but the methods unique. This point moves beyond the obvious differences such as climate and natural resources—intellectual and social dynamics of communities should be investigated as well.

The Davis, CA development featured at the beginning of this report was situated adjacent the Univ. of California campus and many residents were employees of the University. It follows that residents were more likely to accept the designers’ proposals because many were employed in academia and thus accustomed to a more progressive atmosphere. When appropriate, specific design examples that are in use today are presented to motivate creative thought.

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A house is primarily a shell that moderates or buffers occupants from uncomfortable temperatures. A house provides psychological comfort to its residences because its surroundings are constant and familiar. A house is primarily a structure that insulates a body of air in an interior air space. The human body is comfortable between 60-80ºF and about 50% relative humidity. Therefore, an architect provides insulation and auxiliary heating and cooling to maintain an adequate temperature and humidity range. The energy cost to the user and the resource cost to the environment can be reduced if a designer can minimize the heat that must be added or taken away. A few considerations concerning heat loss and heat gain are in order. A structure looses heat through conduction, radiation, convection and infiltration. Conduction is the transfer of heat through a material due to molecular activity tending toward equilibrium. Radiation is energy transmitted directly through space. Convection is the transfer of heat via the movement of fluids such as air or water. Infiltration is the displacement of cold air for warm air due to openings in a structure. Thus to minimize heat loss in a structure we must address primarily address conduction, convection and infiltration.

A structure looses heat through conduction. Heat loss is proportional to the area times a given temperature gradient. Heat loss = ΔT*A*U where U is a materials ability to conduct heat.4 More familiar is the “R” value or resistance value defined as 1/U and is a measure of the material’s ability to impede the flow of heat. Walls in conventional homes are typically R-11 and roofs R-19. Normal windows tend to have R-2 or R-3. Thus windows tend to transmit the most heat and are problematic if not properly designed. These values are important because increasing the R-value decreases the heat loss proportionally. Thus to minimize heat loss one must increase the R value of a material or decrease the area between a temperature gradient. The difference in temperature is a function of the climate, season and time of day and is likely outside of the control of the homeowner.5

Convection heat losses are more difficult to model. Convection losses are a

function of area, wind velocity and the temperature of the fluid that moves over the surface. In the case of residential construction, convection losses are minimized by reducing the area exposed to wind currents and reducing the drag created by the profile of the structure. Landscaping the perimeter of a building by providing vegetation to obstruct the flow of wind across a structure is one way of minimizing convection losses. Infiltration losses are reduced by ensuring that the structure has no leaks or holes through which cold air may enter. Infiltration losses may be reduced by properly sealing all doors and windows and ensuring that the openings to the structure (such as air vents to the attic) are in insulated areas of the house. Heat loss is great through infiltration losses. A study

4 Booth, Don, Sun/Earth Buffering System/ Super Insulation, Community Builders, 1983, p 9. 5 Ibid.

Energy supply/ efficiency

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by Colorado State University concluded that, “In well insulated houses, air infiltration can account for up to 40 percent of the heat lost.”6 Consider two structures. One is a cube and the other is a dome or half sphere. A given cube that encloses 1 m3 of volume will have sides that measure 1 m x 1 m x 1m. The cube is exposed to the air (the temperature gradient) on 5 of its sides because the ground has is not counted. Therefore the area exposed to the atmosphere is 5 * 1 m2 = 5 m2.

However, a dome that encloses 1 m3 of volume will have a radius of approximately 0.61 m. The area exposed to the atmosphere is 2*Π*R2 or 2*Π*(0.61)2 = 3.84 m2. Apparent from this calculation, a dome encloses the same amount of volume with 23% less surface area. A sphere is the most efficient geometric structure if one wishes to enclose the maximum amount of air for a given surface area. Unfortunately, a sphere is difficult to construct and would be too expensive to build in residential construction applications. But builders may approximate a sphere by a dome that consists of a basic shape such as a rectangle or pentagon that is repeated regularly.

Thus, to minimize heat loss and improve energy efficiency it has been shown that

we minimize surface area, minimize the surface area exposed to wind currents and maximize the construction materials’ resistance to heat loss.

6 Walker, L.R, The Sun-Tempered Super Insulated House, Colorado State University, available at http://www.ext.colostate.edu/pubs/consumer/09936.html

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Designing to Maximize Energy Efficiency

One must design to mitigate heat loss or to increase heat gain according to the needs of the homeowner in a given climate. The methods of minimizing heat loss are through improving insulation and decreasing infiltration. Both are accomplished through careful design in the planning stages and attention to detail as the house is being built. Heat gain in cold climates is accomplished through active and passive heat gain systems. Passive systems rely on the sun to warm the interior of a house or working fluid. Active systems utilize the sun’s energy to heat a working fluid and then use a pumping system to transfer the heat through the building’s interior. A discussion of active and passive solar systems follows a look at super insulated houses. Super insulated Houses

Heat loss can be minimized by improving the insulation. A super-insulated house is a description of a structure that is insulated to such a degree that inside temperatures remain fairly constant despite considerable temperature gradients. A builder with 35 years experience in the residential construction industry describes a super-insulated house saying, “It neither gains nor loses much heat. Super insulated houses frequently require almost no supplemental heat, even in cold climates. Most of their heating needs are met by the building’s internal gains—intrinsic heat sources such as the body heat of occupants and the heat given off by cooking stove and electrical appliances and lights.”7 The section details in Fig. 4 show the attention to detail that must be given in the construction of super-insulated walls. Gaskets must be placed to seal from infiltration. Typically 2” rigid insulation is provided over the entire house to prevent infiltration and to maximize the R-value of the sheath. Typical R-values may be 25-30 for the walls and R-40 to R-60 for the roof. The insulation in the roof can be accomplished through 12” thick loose fill. The following are employed in super insulated structures:

• Glazing: often double or triple paned; desiccant sealed between sheets of glass to prevent moisture condensation

• Walls: double walls with fiberglass insulation, framed with 2x6 studs.

7 Booth, p 17.

Figure 4 Super Insulation Wall Details

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• Floors, sills & ceilings: filled with loose insulation and gasket sealed to increase R-value and prevent infiltration

• Double drywall on interior walls for thermal mass to retain heat • Rigid insulation surrounding perimeter of house • Open floor plan to prevent adequate air flow for ventilation

A super insulated house typically costs 5-8% over the cost of typical construction. These costs will be returned through lower (or absent) monthly utility bills. A brief economic analysis follows in ensuing sections to find out the duration to bring a given return and make a super insulated house a viable option. Passive Solar Gain Houses This type of energy efficient design utilizes the sun to heat interior spaces by orienting the house properly and using thermal mass to store heat. The primary characteristic of a passive solar gain house is a southern orientation to allow direct sunlight in the winter months to strike the house on a large glass expanse. The sunlight heats the interior spaces via radiation and conduction. The energy that strikes a house’s south facing wall in the wintertime can contain as much energy as an equivalent of 11 gallons of gasoline.8

A proper orientation of the house (see Fig. 5) will allow as much heat as possible to enter the house during the winter and to minimize heat gain during the summer. Windows should be minimized on the east and west faces where sunlight strikes at intense levels during the summer. During the summer months, one may design the south facing wall with vegetation on an arbor for example that will block the sun when the leaves are in bloom. By winter time, the leaves will have fallen allowing incident radiation to enter.

8 Bainbridge, p 34.

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Figure 5 Southern orientation allows for maximum sunlight in the winter months.

A second design principle is the utilization of storage materials for thermal

warmth and coolth retention. Materials have varying capacity to store heat and then release it to the environment. Water and concrete are both effective for retaining heat. For instance, water can be stored in metal drums and positioned in an interior space to absorb incident energy. It then radiates it back into the room when temperatures drop such as at night. Concrete is effective for thermal storage mass because it can be used structurally such as in a floor slab. As long as the slab is not carpeted it retains energy quite well. A trombe wall or sunspace is a feature of some passive solar designed homes if large south facing glass with a view into the interior is not desired. A trombe wall consists of an outer exterior wall and an inner wall. The space between is usually left unfilled. The outer wall is painted or coated in a dark color to absorb solar radiation and conduct it to the interior space. The outer wall may also be glass depending on the design. The interior space can become quite hot, as much as 100ºF. Natural convection cycles are utilized to move the hotter, lighter air upward as it is replaced by cooler denser air that is drawn from the bottom of the trombe wall. A feature of some passive solar gain homes are small greenhouses that utilize the south facing glass and take advantage of warm temperatures to provide a meager year round food supply. The living space is enhanced by vegetation and seating or tables can be included. Heat can be retained in large metal water filled drums and radiated back at night when temperatures fall. Often auxiliary heat is not necessary even in rooms with large window expanses. When a home is designed to be energy efficient often there are unanticipated returns to the homeowner such as a pleasant interior space. This illustration demonstrates the synergy, or positive unanticipated returns from smart design.

Water heating may be accomplished passively. Water is heated in remote locations and then transported for use in the household. Two examples of solar water

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heating are the “bread box” design and the thermosiphon. The breadbox is a dark box that faces south and absorbs the sun’s energy. Large drums heat water in the interior of the bread box and the water is gravity fed into the house. It can be pumped if necessary. A thermosiphon is usually a flat array of pipes exposed to the sun. The water is heated and rises (warm water rises while cool water falls) and is stored in a tank until it is needed. The preheated water can be heated to a desired temperature in a conventional, energy efficient water heater—which will save energy. A thermosiphon and “bread box” are unconventional structures that can be built from common materials and both are advantageous for acquiring the sun’s free energy.

Figure 6 (left) breadbox design (right) passive solar heating

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Active Solar Heating Systems The principles in active solar heating systems are the same as in passive systems however the working fluid, usually air or water, mechanically moves heat to locations where it is desired. The active system can be used to move heat produced in sun spaces or trombe walls when natural convection cycles cannot induce movement of heat. The active solar heating system of the future is the photovoltaic array. Photons from the sunlight strike a silicon plate causing an electron to be emitted. The electrons induce a current because of the potential difference created between two plates. The following figure illustrates the photovoltaic system:

Photovoltaic arrays allow the homeowner to install a clean electricity supply technology and be completely independent from the utility grid. As of the year 2003, in some states, it can be cost effective to install a photovoltaic array. In the states of New Jersey, for example, the state will subsidize the cost of installation.

Figure 7 (left) The diagram illustrates the function of the photovoltaic array. Electrons strike the plate inducing a current. The energy may be stored for later use in conventional batteries. (right) The solar cell up close. Solar arrays are gaining popularity in schools where energy demands and peak availability usually coincide.

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Elements of active and passive solar gain can be combined in one whole system to effectively heat an entire house with solar power. Auxillary heat systems can be provided that burn on clean gasses. One example is an integrated system that uses a propane water heater as the sole auxillary heat source. The following diagram illustrates a whole systems approach:9

In summary of energy efficient design, most energy savings accumulates through smart planning which includes site orientation, selection of adequate insulation and addition of sunspace or thermal mass storage units to facilitate the distribution of solar heat. Proper placement of windows can aid in heat gain during the winter and provide day lighting to reduce the electricity required to illuminate the interior. Whole systems design asks how technologies can be combined to maximize benefits to the homeowner. Financial analysis demonstrates that it can be cost effective in 2003 to install a completely off-the-grid solar energy supply. In the future, the demand for solar based systems will increase due to falling production costs for photovoltaic arrays and the increased sensitivity to disruptions or shortages in petroleum supply.

Figure 8 Passive solar gain is used on the south facing wall to absorb sunlight. A PV array collects energy on the roof. A heat exchanger takes heat from laundry and bathrooms and conducts it to ventilated air. Demonstrates compatibility of active and passive design.

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A residential development produces waste in several forms. The largest component of waste is construction waste. Waste byproducts of a household include paper, plastic, steel and small amounts of toxic materials. Sewage and grey water are two different types of liquid/ solid waste produced by humans. Waste management presents opportunities to employ sustainable methods.

Current models of waste removal and management are unsustainable because they rely on large centralized transport dependent systems. Methods must be employed to deal with waste more effectively if development is to be managed more sustainably. This section of the report describes each type of waste and how planners and managers can minimize its impact on human and biological systems. Construction Waste and Embodied Energy

Construction waste occurs in the building phase when timber, concrete and other materials are trimmed or fashioned to be put in place. Construction waste accumulates in the demolition or rebuilding phase when a house is removed to be replaced with another structure after its useful life expires.

The term embodied energy describes the energy that goes into the entire life cycle

of a building material.10 Embodied energy and useful life are two important characteristics of construction materials. To minimize the impact of construction waste, designers must minimize the embodied energy of the materials they select and increase the useful life.

Concrete is an example of a material that has a relatively low embodied energy

(neglecting labor for formwork) and a high useful life. It can be recycled—though the process is energy intensive because the concrete must be crushed to produce aggregate. Aluminum has a high embodied energy but an extremely high useful life. It can be easily recycled.

The methods for the reduction of construction waste include:11

• Adapt Existing Houses to New Uses: Once a home has outlived its useful life, sections of the house can be reused or the new design can incorporate the old structure. The embodied energy of an existing structure is very high and if it can be preserved the energy will be saved in the demolition and reconstruction process.

10 Kim, Jong-Jin, Introduction to Sustainable Design, University of Michigan, National Pollution Prevention Center for Higher Education, available at www.umich.edu/~nppcpub/, p19. 11 Op Cit, p 21.

Waste treatment/ management

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• Incorporate Reclaimed or Recycled Materials: Markets exist in some cities for all manner of construction materials. Wood, steel and glass can be easily recycled. Most of the furnishings can be reused.

• Use Materials that can be Recycled: When the house is being designed, select

materials that can be recycled to reduce the amount of waste that will have to be deposited in a landfill.

• Design Homes to Standard Dimensions: studs, plywood, windows and doors

are examples of components that come in standard dimensions. By designing for those dimensions, the designer can reduce waste.

The house must be designed with its life cycle in mind. A building has three

phases: pre-building, building and post-building. Waste reduction methods can be employed at any phase in the Life Cycle of a building. Consumer Waste By-Products Nature produces no waste as each process produces a product that becomes an input for another process. Waste loops are cyclical rather than linear. However, modern society has largely adopted a waste model that begins with production and ends in a landfill. Waste recycling represents a high potential for profit because the molecules in a finished product are already highly organized.

It is in humanity’s interest to design with the product’s life cycle in mind so that recycling becomes easier. For example, Interface a leading carpet manufacturer has begun to design carpet with the life cycle in mind. The company has produced a carpet whose polymer chains can be easily broken down and refashioned into a new product. Old carpet becomes the input stream for new carpet. The incentive to dispose of the old carpet now lies with both the owner of the carpet and the producer. The owner wants money for the old carpet because it is valuable. The producer wants to reclaim the carpet to produce new carpet. Incentives to recycle exist on both the consumer and producer end. This example illustrates the basis for conversion from a product based economy to a service based economy. Instead of buying carpet and disposing of it years later, one would buy carpet service. Each year the homeowner would pay a fee and after so many years, the carpet would be replaced.

The waste produced by human consumption can be reduced through extensive recycling programs that encourage separation of materials and active participation in existing programs. Communities must employ active reward programs for recycling and facilitate the removal of products in a timely manner. Income derived from recycling programs can be put into community infrastructure which promotes the criteria of sustainable design that values community belonging. Sewage and Grey Water Sewage and grey water are primarily liquid based components of household waste. Both types of waste run through sewage lines in a conventional waste model

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before they are treated remotely. However, sewage contains bacteria and pathogens that are harmful to human beings. Grey water constitutes the runoff from bathtubs, sinks and storm water that is potentially benign to humans. Sustainable design in waste treatment involves differentiating between the two types of waste. One tenet of sustainable design is to minimize paved surfaces primarily because pavements are petroleum based and require high energy inputs. However, pavements impede the penetration of water to the subsoil and increase the likelihood of erosion. Pollutants from the surface sources enter the drainage network and increase the likelihood of contaminating the local watershed. Designers should minimize paved surfaces and provide areas where water may enter the soil to allow the contaminants to be filtered by natural processes. Natural drainage swales, constructed wetlands and vegetated creek beds provide ecological systems that promote the bio-remediation of surface wastes. When appropriate, surface runoff should be directed to naturally vegetated areas. A constructed wetland must consider the number of occupants and the loads that will be developed. Typically wetland construction is appropriate for small neighborhoods where land is readily available. The following schematic diagrams illustrate the concept of a constructed wetland.12

Figure 10 Waste is processed in septic tank to remove solids. Effluent travels to constructed wetlands to be processed through bioremediation.

Once the loads from the households can be determined a rational analysis can be

performed to determine the daily flow to the constructed wetland. The wetland must be

12 Individual Residence Wastewater Wetland Construction in Indiana, Catherine Taylor, Don Jones, Joe Yahner, Michael Ogden, and Alan Dunn, Agronomy and Agricultural Engineering, Purdue University, available at http://pasture.ecn.purdue.edu/~epados/septics

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vegetated properly and the effluent must be able to seep to the roots of the plants. Adequate oxygen and nutrient content must be available for the oxidation of waste products. The following figure is a conceptual drawing of a wetland:

Figure 11 Schematic of Constructed Wetlands

Appended to this report is a wetland design for a residential house. The house is a dome home and the floor plan for the house is included. The house and wetland presents the application of several design features discussed in this report to increase the sustainability of residential development. Waste reduction and management measures need to be readdressed to be made sustainable in modern development. Linear waste streams must be redesigned into cyclical waste streams where the waste becomes the input for the next process. Advanced recycling programs accomplish this goal until the responsibility for the reuse of the product is transferred to the manufacturer. Natural waste treatment systems—constructed wetlands are an example—accomplish the same goals without the energy requirement of large infrastructure.

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Summary of Sustainable Residential Development

21st century communities must aim for standards of sustainability in order to meet the growing demand for housing in a world with finite resources. In the next quarter century, designers and planners must facilitate a shift in the traditional “suburban sub-development” paradigm. Neighborhoods are structures that subconsciously communicate ideas. In order to shift conventional thinking we must begin locally with the character of our neighborhoods.

A residential development must change from a parcel of land sub divided to accommodate a maximum number of houses to a locally managed collective of houses intentionally concerned with human well-being. Development must be profitable. But conventional development neglects the health of human and social systems.

New development might include locally managed health clinics, day care

facilities and early education centers within walking distance of new homes. Every aspect of the community must be designed to enhance the social health of the community. Sustainable residential communities are those which meet the current occupant’s needs without compromising their children or grandchildren’s capacity to meet their own.

Such communities are characterized by a “systems” approach to land

development and resource utilization. They employ clean technologies whose holistic approach creates market demand for such a lifestyle. This market has been proven across the United States, but must become standard for new development in the United States.

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APPENDIX

Built Green Communities Checklist

• A list of criteria used by developers to preserve resources, balance density issues and encourage effective, innovative ideas

Wetlands Design for Residential House

• A design for a residential house that utilizes a septic and natural wetland

system to process waste

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